NASA'S Chandra X-ray Observatory Reveals New Insights On Westerlund 1, Milky Way’s Largest 'Super' Star Cluster

Currently, star formation in our galaxy is occurring at a slower pace with only a few stars being formed each year. However, 10 billion years ago when the galaxy was at its peak the rate of star formation was much higher and the galaxy was producing at least hundreds of stars each year.

A ‘super’ star cluster which is the largest and nearest to Earth, well near according to astronomical measurements, is being thoroughly examined and observed with new data that was received from NASA’s Chandra X-ray Observatory and a couple of other NASA telescopes. The supercluster is identified as Westerlund 1 and is currently being observed by astronomers in detail as it is an active start-producing region.

The Extended Westerlund 1 and 2 Open Cluster Survey(EWOCS) is the name of the project under which observations have been carried out and the recently released data marks the project’s first public release. Astronomers from the Italian National Institute of Astrophysics in Palermo lead EWOCS. Chandra dedicated approximately 12 days to observing Westerlund 1 as part of this project.

Currently, star formation in our galaxy is occurring at a slower pace with only a few stars being formed each year. However, 10 billion years ago when the galaxy was at its peak the rate of star formation was much higher and the galaxy was producing at least hundreds of stars each year. Most of this star formation activity took place inside a ‘super’ star cluster like Westerlund which is currently under observation. These clusters are young and Westerlund is approximately 3-5 million years old and contains over 10,000 times the mass of the sun.

The new image combines extensive data from Chandra and previous observations from NASA’s Hubble Space Telescope. Chandra’s X-ray data reveals young stars and diffuse, heated gas within the cluster. The young stars predominantly appear white and pink, while the heated gas is depicted in pink, green, and blue, indicating increasing temperatures. Hubble’s data highlights numerous stars as yellow and blue dots.

There are a few super star clusters that exist in our galaxy to date, and the study of these clusters provides valuable information about the time when most of the stars in our galaxy were formed, Westerlund 1 being the largest such super star cluster in Our Milky Way galaxy. This cluster is closest to Earth and is approximately 13,000 light years away.

What Does The Data Reveal?

The data received from Weterlund through Chandra has immensely increased the number of known X-ray sources in the super star cluster. About 1721 X-ray sources were detected by Chandra in Westerlund previously. The new data has revealed at least 6000 sources with the presence of faint stars having less mass than Our sun. The data has opened up the venue for astronomers to conduct research with a new population of stars altogether.

A remarkable finding reveals that the core of Westerlund 1 is densely packed with 1,075 stars within a four-light-year radius. For context, this distance is equivalent to the gap between our Sun and its closest neighbouring star. The EWOCS data has revealed diffuse emissions that have led to the detection of a halo of high-temperature gas centered around Westerlund. This is crucial information to understand the cluster’s formation and evolution and will also help in estimating the mass of the cluster.

About Chandra X-ray Observatory

The Chandra X-ray Observatory abbreviated as CXO is a flagship-class space telescope launched on July 23, 1999. The Chandra X-ray observatory has the capacity to detect X-rat sources that are 100 times fainter than any previous X-ray telescopes, because of the high angular resolution of its mirrors. Detection of X-rays on Earth is difficult as most of these rays get absorbed by the Earth’s atmosphere, therefore space-based telescopes are used to make these observations.

Chandra is an Earth satellite in a 64-hour orbit and continues its mission as of 2024. It is one of the Great Observatories, alongside the Hubble Space Telescope, the Compton Gamma Ray Observatory (1991–2000), and the Spitzer Space Telescope (2003–2020). The telescope is named after Subrahmanyan Chandrasekhar, the Nobel Prize-winning Indian astrophysicist.

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